Problem: $-4\dfrac{1}{2} \div \left(-1\dfrac{3}{8}\right) = $
Solution: Let's start by converting the mixed numbers to fractions. $\phantom{=}-4\dfrac{1}{2}\div-1\dfrac{3}{8}$ $=-\dfrac{9}{2}\div\left(-\dfrac{11}{8}\right)$ $=-\dfrac{9}{2}\cdot\left(-\dfrac{8}{11}\right) ~~~~~~~\text{multiply by the reciprocal}$ $=-\dfrac{9}{{1}\cancel{2}}\cdot \left(- \dfrac{{4}\cancel{8}}{11}\right)$ $=-\dfrac{9}{1} \cdot \left(-\dfrac{4}{11}\right)$ $=\dfrac{36}{11}\text{ or }3\dfrac3{11}$